Combining a Gas-Injection System (GIS) with the Focused Ion Beam (FIB) has a broad scope of applications in sample preparation such as protective layer deposition, increasing material sputtering rates and reducing FIB-related artefacts. On the other hand injecting certain specific gases during a Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) analysis can significantly increase element ionization probability and, therefore, improve the quality of 3D representation of a sample elemental structure. In this work, for the first time the potential of GIS for enhancing secondary ion signals acquired using a TOF detector incorporated into a commercial Ga + FIB-SEM (Focused Ion Beam combined with Scanning Electron Microscope) instrument is presented. The depth profiles of pure metals (thin films of Cu, Zr, Ag and W with the thickness in the order of 100 nm) were acquired at ambient vacuum conditions as well as under an exposure to water and fluorine gases. The influence of supplementary gases on the ion yields and sputtering rates were studied. Simulations were performed to assess the local gas pressure at the location of FIB-TOF-SIMS analysis. The highest enhancement of ionization probability was achieved in the case of the Cu thin film (10 times during water co-injection and 510 times when using a fluorine gas). Regarding the sputtering rates, the response of Zr to effect of the gases was the strongest. Comparing to a standard background pressure measurements, this thin film was milled around 6 times faster under the exposure to a water vapor and over 2 times faster when fluorine gas was supplied.

Investigation of the matrix effect in Zr-based two-element alloys under continuous bombardment of a Ga+ primary ion beam in a study of ionization probability towards exploring the potential and limitations of gas-assisted TOF-SIMS.

Imaging nano-objects in complex systems such as nanocomposites using time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a challenging task. Due to a very small amount of the material and a matrix effect, the number of generated secondary ions can be insufficient to represent a 3D elemental distribution despite being detected in a mass spectrum. Therefore, a model sample consisting of a ZrCuAg matrix with embedded Al nanoparticles is designed. A high mass difference between the light Al and heavy matrix components limits mass interference. The chemical structure measurements using a pulsed 60 keV Bi 3 2+ beam or a continuous 30 keV Ga + beam reveals distinct Al signal segregation. This can indicate a spatially resolved detection of single 10s of nanometer large particles and/or their agglomerates for the first time. However, TOF-SIMS images of 50 nm or smaller objects do not necessarily represent their exact size and shape but can rather be their convolutions with the primary ion beam shape. Therefore, the size of nanoparticles (25−64 nm) was measured using scanning transmission electron microscopy. Our studies prove the capability of TOF-SIMS to image chemical structure of nanohybrids which is expected to help building new functional materials and optimize their properties.

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) detectors have been intensively developed in recent decades due to their unprecedented capability of representing a sample elemental composition in a 3-dimensional space from nano-to submili-scale with high spatial resolution and mass resolution. A compact high-vacuum-compatible version of these detectors can be integrated into a Focused Ion Beam (FIB) system which, assembled with Scanning Electron Microscopy (SEM), is the most popular tool used in nanotechnology and material science. This gives a new opportunity for combining TOF-SIMS analysis with other instruments within the same analytical chamber. In this work we present the results of conducting elemental characterization of a dedicated model multilayer sample composed of 100 nm thick thin films of Cu, Zr and ZrCuAg alloy in a fluorine gas atmosphere provided by an in-situ Gas Injection System (GIS). In general, the secondary ion signals were significantly enhanced by up to three orders of magnitude leading to much higher spatial resolution. The quality of elemental images and depth profiles was improved during a single measurement (which usually cannot be obtained at standard vacuum conditions) at high beam energy of 20 keV. Moreover, fluorine assistance has enabled a mass interference between 107 Ag + and 91 Zr 16 O + ions to be separated. This remarkable finding has never been reported before and is expected to play an important role in the future evolution of TOF-SIMS analytical protocols as currently the mass interference between ions remains one of the main drawbacks of the technique.